#include <stdio.h>
void swap(int*x,int*y){
    int i=*x;
    *x=*y;
    *y=i;
    }
int main()
{
    int a,b;
    a=25;
    b=75;
    printf("befor :\n");
    printf("a=%d\n",a);
    printf("b=%d\n",b);
    swap(&a,&b);
    printf("after :\n");
    printf("a=%d\n",a);
    printf("b=%d\n",b);
  return 0;
}
